Aircraft surge when starting . . .

When I start a new flight, whether my first flight after opening FSX or any subsequent flight thereafter, my aircraft surges forward momentarily and the engines sound as if they are spooling down (instead of starting at idle). This is most significantly a problem with airliners, but occurs with all aircraft. If I am starting out at a gate or otherwise near a building, I think you could see how even small surges forward could be a real problem.
Any ideas of what causes this and how it can be corrected?
Many thanks,
Darrin
Any ideas of what causes this and how it can be corrected?
Many thanks,
Darrin